This was unexpected. Byron Dorgan, the Democrat who served North Dakota in the US Senate for 30 years, will not seek re-election. Here’s the statement posted at his Senate site.

“Representing North Dakota in the U.S. Congress for nearly 30 years has been one of the great privileges of my life.

“The work I have been able to do to expand our economy, create new opportunities in energy and water development, invent the Red River Research Corridor with cutting-edge world class research, build a stronger safety net for family farmers and much more has been a labor of love for me [...]

“Although I still have a passion for public service and enjoy my work in the Senate, I have other interests and I have other things I would like to pursue outside of public life. I have written two books and have an invitation from a publisher to write two more books. I would like to do some teaching and would also like to work on energy policy in the private sector.

“So, over this holiday season, I have come to the conclusion, with the support of my family, that I will not be seeking another term in the U.S. Senate in 2010. It is a hard decision to make after thirty years in the Congress, but I believe it is the right time for me to pursue these other interests.

This is a major blow to Democrats in the Senate. Aside from Dorgan being a pretty solid champion for the middle class, in the populist prairie tradition, he represents a state that is pretty solidly Republican (although Barack Obama actually did half-decent there in 2008). John Hoeven is one of the most popular Governors in the country, and if he jumped into this race – which is pretty likely – I think he would win in a walk.

That’s an almost certain flip to the Republicans in the Senate, one they probably won’t even have to spend very much to get, and it really frustrates any opportunity for Democrats to maintain their 60-seat advantage. This is basically the last year of governing for the Obama Administration for the discernible future, especially as Democrats will have far more seats to defend in the Senate in 2012 and 2014. And they’ve already hinted that there will be almost no governing this year.

UPDATE: Marcy Wheeler hints that this could be fallout from Dorgan’s loss on reimportation. I don’t really buy that. Dorgan’s fought a lot of lonely battles in his day, and he never gave up before. He was practically the only member of the Senate who didn’t want to repeal Glass-Steagall. If that kind of cynical legislating didn’t get him out, I doubt the PhRMA deal would have. Occam’s razor here is that Dorgan’s an old man and he wanted to enjoy his later years. I do think that, with the expectation of a less-than-60-vote Senate in the near future, which is the likely outcome after the midterms, he saw no real point to sticking around.